In view of improved yield in semiconductor fabrication, management of the surface condition of a peripheral portion of a substrate such as a silicon wafer has been gathering attention. That is, in steps of semiconductor fabrication, many materials are deposited on a front surface (device surface) of the substrate to form a device. However, in the fabrication steps, an unwanted film or a roughened surface may be formed in a peripheral portion of the substrate. In addition, in recent years, a method for conveying a substrate with a peripheral portion thereof held by an arm has been common.
In such a background, as various steps are carried out, an unwanted film remaining in the peripheral portion may be peeled off and attached to the device, leading to reduced yield. Thus, a polishing apparatus is conventionally used to polish the peripheral portion of the substrate to remove the unwanted film or the roughened surface.
The peripheral portion of the substrate is polished by, for example, sucking a central portion of a back surface of the substrate to a stage to support the central portion and pressing a polishing tape, a grinding stone, or the like against the peripheral portion of the substrate while rotating the stage.
More specifically, the peripheral portion of the substrate is generally polished by first coating the front surface and back surface of the substrate with a rinse liquid (polishing liquid) such as pure water, and after the front surface and back surface of the substrate are coated with the rinse liquid, pressing the polishing tape, the grinding stone, or the like against the peripheral portion.
In this case, the coating of the rinse liquid may be carried out by feeding the rinse liquid through a front surface rinse nozzle disposed opposite the front surface of the substrate and feeding the rinse liquid through a back surface rinse nozzle disposed opposite the back surface of the substrate, while rotating the stage. The rinse liquid fed to the front surface and back surface of the substrate flows toward the peripheral portion of the substrate by a centrifugal force resulting from the rotation of the substrate. Thus, the front surface and back surface of the substrate are coated with the rinse liquid.